How do you guarantee that your iPhone App hits number one in 57 countries? If the Barclaycard-branded game “waterslide” is any indication, the key is to create a game that mirrors a successful ad.

Of course, it’s not that easy but “Waterslide” has followed that formula to the tune of 3 million downloads in just 13 days.

If you’re not familiar with “Waterslide”, it’s a game that positions you (male or female) on a waterslide and the object of the game is to collect as many items as you can as you go down the waterslide. Steering is done by tilting the iPhone and there are also obstacles that slow you down.

The “Waterslide” game is free and to be honest, I didn’t even notice the branding or the similarity to the ad–I was just intrigued by the game play, sound effects, and music. That said, score one for Barclaycard since they managed to get their branding out there without knocking the consumer over the head with it.

Read more about Waterslide’s success at Pocketlint and watch the video of the game in action below.